JP2000306434A - Overhead transmission cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overhead transmission cable having practically satisfactory wind-whistle characteristics and corona characteristics, and having a surface to which snow is less to stick. SOLUTION: This overhead transmission cable is made by twisting aluminum wires 4 together with steel wires 2, and twisting molded strands different from each other in height as part of the outermost strand layer to form a protrusive high-step projection part 8 and a low-step smooth part 10 on a surface of the cable. The depth H and the opening width t of dents 12 formed between the respective molded strends 5 forming the low-step smooth part 10 of the outermost layer of the overhead transmission cable 1, satisfy 0.7 mm<=H<1.5 mm, t/H>=3, and t>3.0 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overhead power transmission line, and more particularly to an overhead power transmission line with low wind noise and corona noise.

[0002]

2. Description of the Related Art Conventionally, as an overhead transmission line, as shown in FIG. 9, an aluminum wire 93 is provided around the outer periphery of a steel core 92 comprising one or a plurality of steel wires 91 which have been protected by Zn plating or the like. (Australia steel strand stranded wire) 94 which has been mainly used. Usually, as the aluminum strand 93, one having a round cross section is used because it is easy to manufacture.

[0003] However, when wind hits the overhead transmission line composed of the ACSR 94, wind noise (so-called wind noise) is generated. This wind noise may cause discomfort to the residents in the transmission line passage area, and may cause a noise problem. For this reason, it is necessary to reduce wind noise in overhead transmission lines passing through plains (residential areas, agricultural lands) and the like, and low wind noise electric wires having high step projections on the surface of the electric wires are used.

[0004] Further, during rainfall, water droplets adhere to the surface of the low-level uneven portion of the electric wire, and corona noise (Audible Noise) is generated due to the water droplets. In recent years, the transmission voltage of the overhead transmission line has been increasing to an ultra-high voltage or an ultra-high voltage, such as 500 kV to 1000 kV,
Since the potential gradient (Gmax) on the electric wire surface is increasing, measures for reducing corona noise are also required.

In order to suppress wind noise, as shown in FIG. 10, a high step projection 102 is formed on the surface of an electric wire 101 having an outer diameter D _3.
Is known to be effective. The opening angle of the level difference h ₂ and the high step protrusion 102 of the high-stepped protrusion 102 and the lower stepped flat portion 103 has a valid range,
According to the study of the present inventors, in the overhead transmission line 101 which is usually used, the step h ₂ is ₂ to 4 mm, and the opening angle θ
Is preferably 20 to 60 °. Further, in order to further enhance the wind noise reduction effect, the depth of the depression (not shown) formed between the aluminum wires (not shown) forming the low step smoothing portion 103 is as small as possible, and the electric wire surface It is desirable that there are few irregularities.

[0006]

However, if the unevenness of the surface of the electric wire is reduced to further enhance the effect of reducing the wind noise, the water droplets can easily stay in the low-level uneven portion 103 during rainfall, and the "water drainage property" of the electric wire is reduced. Is worse. As a result, there is a problem that if the improvement of the wind noise characteristics is emphasized too much, the corona characteristics are deteriorated.

For this reason, in order to suppress corona noise caused by water droplets staying in the low step smoothing portion 103, the depth of the depression on the surface of the low step smoothing portion 103 is intentionally increased to improve the "water drainage" of the electric wire. A low-noise electric wire has been proposed.

However, an overhead transmission line in a snowfall area (particularly in a heavy snowfall area) is an electric wire having good wind noise characteristics and corona characteristics, and is also a wire on which snow hardly adheres to the surface (has good snow-resistant characteristics). Although it is essential, the fact that the depth of the depression is large means that the cross-sectional shape is A shown in FIG.
Since it is close to CSR94 and it is easy to catch snow in the dents, it is far from an electric wire having good snow-resistant characteristics.

It is an object of the present invention to provide an overhead power transmission line which solves the above-mentioned problems, has practically sufficient wind noise characteristics and corona characteristics, and hardly causes snow on the electric wire surface.

[0010]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention of claim 1 comprises twisting an aluminum wire and a steel wire, and twisting formed wires having different heights on a part of the outermost wire. In addition, in an overhead transmission line in which a high step projection portion and a low step smooth portion which are projections are formed on the surface, the depth of a dent formed between the formed wires forming the low step smooth portion of the outermost layer of the overhead transmission line. H and opening width t are 0.7 mm ≦ H <1.5 m
m, t / H ≧ 3, and t> 3.0 mm.

According to the above configuration, it is possible to obtain an overhead transmission line in which snow does not easily reach the surface of the electric wire while maintaining good wind noise characteristics and corona characteristics.

According to a second aspect of the present invention, the cross-section of the forming wire forming the low-level-smooth portion is substantially adjacent to the smooth outer end surface forming the outer peripheral surface and the inner end surface forming the inner peripheral surface. It is formed with both side end surfaces having straight portions that are aligned in the radial direction of the electric wire so as to be in close contact with the formed wire, and the inner peripheral surface side corners connecting both the straight portions on both side end surfaces and the inner end surface and the two side end surfaces are formed. 2. The overhead transmission line according to claim 1, wherein a corner on the outer peripheral surface side connecting the linear portion and the outer end surface is formed in a straight line or a curved line, and a recess is formed with the corner on the adjacent outer peripheral surface side.

According to a third aspect of the present invention, the cross-section of the forming wire forming the low step smooth portion is substantially adjacent to the smooth outer end surface forming the outer peripheral surface and the inner end surface forming the inner peripheral surface. It is formed with both side end surfaces having a linear portion that is aligned in the radial direction of the electric wire so as to be in close contact with the formed wire, and the inner peripheral surface side connecting the linear portion of the both side end surfaces and the inner end surface is linear or It is formed in a curved shape, and a corner on the outer peripheral surface side connecting the linear portion on both side end surfaces and the outer end surface is formed in a linear shape, and both ends of the linear portion of the angle are formed in a curved shape, and the adjacent outer peripheral surface is formed. 2. The overhead transmission line according to claim 1, wherein a depression is formed with the corner on the side.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a cross sectional view of the overhead transmission line of the present invention.
FIG. 2 shows an enlarged view of the depression 12 in FIG.

As shown in FIG. 1, one or a plurality of overhead transmission lines of the present invention are provided with corrosion protection by Zn plating or the like (FIG. 1).
On the outer periphery of a steel core 3 composed of seven (7) steel wires 2, a stranded wire layer composed of a molded aluminum element wire 4 having a substantially fan-shaped cross section is formed in multiple layers (two layers in FIG. 1). On the outer periphery (outermost layer) of the stranded wire layer, a section having a substantially fan-shaped cross section and different cross-sectional shapes and
Formed aluminum strands (molded strands) 5, 6, and 7 are twisted to form a high step projection 8 on at least a part of the surface (a diagonal position in the vertical direction in FIG. 1), and The low level difference smoothing part 10 is formed in the remaining part.

The low step smoothing portion 10 is formed by twisting a plurality of (12 in FIG. 1) formed aluminum wires 5, and between the formed aluminum wires 5 as shown in FIG. To
A depression 12 having a depth H and an opening width t is formed. Here, the depth H and the opening width t of the depression 12 are 0.7 mm.
≦ H <1.5 mm, t / H ≧ 3, and t> 3.0 mm
Is satisfied.

The cross section of the formed aluminum wire 5 has a smooth outer end surface 26 which substantially forms the outer peripheral surface (low step smooth portion 10).
And an inner end surface (not shown) serving as an inner peripheral surface, and both end surfaces 27 having linear portions that are aligned in the radial direction of the electric wire so as to be in close contact with the adjacent molded aluminum wires 5. A corner 28a on the outer peripheral surface side connecting the linear portion of both side end surfaces 27 and the outer end surface 26 is formed linearly, and both side end surfaces 27 are formed.
Corner (not shown) on the inner peripheral surface side connecting the linear portion of the
Are formed in a straight line (or a curved line), and the recess 12 is formed by a corner 28a on the outer peripheral surface side of the formed aluminum element wire 5 and a corner 28b on the outer peripheral surface side adjacent to the corner 28a.

The high step projection portion 8 has two molded aluminum wires 6a and 6b which are higher than the molded aluminum wires 5 and a height which is lower than the wires 6a and 6b and which is smaller than the wires 6a. , 6b, and a concave portion 9 is formed at the center thereof due to a difference in height between the wires 6a, 6b and the wire 7. I have. The opening angle of the high step projection 8 is θ.

The outer diameter of the overhead transmission line 1 of the high step projection 8 is D
_1, if the outer diameter of the overhead line 1 of the low stepped smooth portion 10 and a D _2, step h between the high step projections 8 and the low stepped flat portion 10
₁ is defined as (D ₁ -D ₂ ) / 2.

Incidentally, as the aluminum strand forming the stranded wire layer,
In the present invention, each of the layers is a substantially aluminum-shaped formed aluminum wire 4 having a cross section.
However, there is no particular limitation, and a round aluminum wire may be used.
Needless to say, the stranded wire layer may be formed by combining the aluminum wire with a round aluminum element wire.

Next, the operation of the present invention will be described.

FIG. 5 shows the relationship between the opening angle θ (deg) of the high step projection and the reduction amount (dB) of the wind noise level.

The outer diameter D ₂ of the low step smooth portion is the same, and the step h ₁ between the high step protrusion and the low step smooth portion is different (1.0 m).
m, 1.5mm, 2.0mm, 2.5mm, 3.0m
m, 3.5 mm, 4.0 mm) For 7 types of overhead transmission lines, the opening angle θ of the high step projection is 0 to 180 (deg).
Varied and, as a result of step h ₁ and opening angle θ was examined the influence on wind noise level, as shown in FIG. 5, step h ₁ is in the range of 2.5-4.0, good wind noise reduction the effect is obtained, since the level difference h ₁ exacerbates too high a corona characteristics, is preferably about 2.5 mm. When the opening angle θ was in the range of 20 to 60 °, a good wind noise reduction effect was obtained.

The potential gradient on the surface of the overhead transmission line (Gmax (k
V / cm)) and corona hum sound relative level (dB (A))
Is shown in FIG. The line connecting the circles in the figure is A
The line connecting the black circles indicates the type B overhead transmission line, the line connecting the triangles indicates the type C overhead transmission line, and the line connecting the symbols ▲ indicates the type D overhead transmission line. 2 shows an overhead transmission line.

The outer diameter D ₂ of the low step smooth portion is the same, and the step h ₁ between the smooth high step protrusion and the low step smooth portion is different (2.7 mm, 2.3 mm). Two types of overhead transmission lines (B type and D type) having a recess formed in the center of each high level projection of each of the A type and C type overhead transmission lines and the A type and C type overhead transmission lines As a result of examining the influence of the shape of the sound on the corona hum sound level, as shown in FIG. 6, Gmax was 16.5.
In the case of (kV / cm) or less, the B type and the D type in which the concave portion is formed in the high step projection portion have a better corona hum noise reduction effect, and in particular, the Gmax is 1
At 5 (kV / cm) or less, the effect is remarkable.

From the results shown in FIG. 5 and FIG.
To There is formed a high-stepped protrusion 8 step h ₁ between the low-stepped flat portion 10 is 2.5mm approximately, a high step protrusion 8 the opening angle θ satisfies 20 to 60 ° high stepped protrusion 8 By that
Overhead transmission line 1 with good wind noise and corona characteristics
Can be obtained.

FIG. 7 shows the relationship between the depth (mm) of the dent formed between the formed aluminum wires in the low step smooth portion and the corona hum sound relative level (dB (A)). In the drawing, the line connecting the circles indicates the case where Gmax is 14 (kV / cm), and the line connecting the crosses indicates the case where Gmax is 15 (kV / c).
m).

Outer diameter D of overhead power transmission line 1 of low step smoothing section 10
_{2 while} keeping the same, the depth H of the depression 12 between the formed aluminum wires 5 was set to 0.3 mm, 0.5 mm, 0.7 mm, 1.0 mm.
mm, 1.5 mm, and 2.0 mm, and the effect of the depth H of the depression 12 on the corona hum sound level was examined. As shown in FIG. 7, Gmax = 14 and Gmax
= 15, the depth H of the depression 12 is 0.7
mm, a good corona hum sound reduction effect was obtained.

Ratio between the opening width t of the depression and the depth H (t / H)
FIG. 8 shows the relationship between the angle and the inclination angle (degree). In the drawings, the line connecting the marks indicates the case where H is 0.5 mm, the line connecting the marks indicates the case where H is 1.0 mm, and the line connecting the marks indicates that H is 1.0 mm. 5 mm is shown, and the line connecting the squares is H
Is 2.0 mm.

After a depression having a depth H and an opening width t is formed in a flat plate, and snow is deposited in the depression, the inclination angle of the flat plate is gradually increased to determine how many times the snow falls. As a result of examining the fall start angle, as shown in FIG. 8, as the depth H of the depression becomes smaller, the fall start angle becomes smaller. In particular, when the depth H is smaller than 1.5 mm, the result that the snow easily falls. was gotten. Also, as t / H increases, the fall start angle decreases, and in particular, when t / H is 3 or more, the result is that snow easily falls. Regarding the range of the opening width t, the aforementioned 0.7 mm ≦ H <
If 1.5 mm and t / H ≧ 3, t> 2.1 mm, but in reality, if the numerical value of t is small, it is technically difficult to achieve both the corona characteristic and the snow-resistant characteristic. Therefore, t> 3.0 mm where both of these effects can be easily achieved.
Is an effective range, and a preferable range of t is 3.5 mm or more.

From the results of FIGS. 7 and 8, the depth H and the opening width t are 0.7 mm ≦ H <1.5 mm and t / H ≧
3, and by forming a dent 12 satisfying t> 3.0 mm between the aluminum wires 5 of the low step smoothing portion 10, the overhead transmission line 1 having good corona characteristics and snow-resistant characteristics is obtained. Obtainable.

That is, according to the present invention, the shape of the high step projection 8, the step h ₁ between the high step projection 8 and the low step smoothing section 10, the opening angle θ of the high step projection 8 and the low step smoothing section 10, the depth H of the depression 12 formed between the formed aluminum wires 5, the opening width t, and the ratio of the opening width t to the depth H (t /
Since H) is set in a predetermined range, it is possible to obtain the overhead power transmission line 1 in which snow does not easily reach the surface while maintaining good wind noise characteristics and corona characteristics.

An overhead power transmission line 1 on which snow does not easily reach the surface
Therefore, even if the overhead transmission line 1 is erected in a heavy snowfall area, snow does not grow on the overhead transmission line 1, and the reliability of the tower and the strength of the electric wire is extremely increased.

Next, another embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 3 shows an enlarged view of the depression 32 in the cross section of the overhead transmission line according to the first embodiment.

In the overhead transmission line of the present invention, corners 28a, 28b on the outer peripheral surface side of the formed aluminum wire 5 forming the depression 12
Was formed linearly.

On the other hand, as shown in FIG. 3, the cross section of the formed aluminum wire 35 forming the recess 32 in the low step smoothing portion 30 of the overhead transmission line 31 of the first embodiment is substantially as shown in FIG. A smooth outer end surface 36 forming an outer peripheral surface (low step smoothing portion 30), an inner end surface (not shown) serving as an inner peripheral surface, and a radial direction of the electric wire so as to be in close contact with an adjacent molded aluminum wire 35. Of the outer peripheral surface 36 connecting the linear portion of the both side end surfaces 37 and the outer end surface 36 in a curved shape. A corner (not shown) on the inner peripheral surface side connecting the shape portion and the inner end surface is formed in a straight line (or a curved line), and is adjacent to the corner 38a on the outer peripheral surface side of the formed aluminum wire 35 and the corner 38a. The depression 32 is formed with the corner 38b on the outer peripheral surface side.

FIG. 4 shows an enlarged view of the depression 42 in the cross section of the overhead transmission line according to the second embodiment.

As shown in FIG. 4, the cross section of the formed aluminum wire 45 forming the depression 42 in the low step smoothing portion 40 of the overhead transmission line 41 of the second embodiment is substantially the outer peripheral surface (low step). A smooth outer end surface 46 forming a smooth portion 40);
An inner end surface (not shown) serving as an inner peripheral surface, and both end surfaces 47 having straight portions which are aligned in the radial direction of the electric wire so as to be in close contact with the adjacent formed aluminum wires 45 are formed. A corner 48a on the outer peripheral surface side connecting the linear portion of the end portion 47 and the outer end surface 46 is formed linearly, and both ends of a linear portion 49 of the corner 48a are formed in a curved shape. A corner (not shown) on the inner peripheral surface side connecting to the inner end surface is formed in a straight line (or a curved line), and a certain formed aluminum wire 45 is formed.
The recesses 42 are formed by the corners 48a on the outer peripheral surface side and the corners 48b on the outer peripheral surface side adjacent to the corner 48a.

Here, one end of the straight portion 49 on the inner end surface side is a curved portion 51 having a predetermined radius of curvature, and one end of the straight portion 49 on the outer end surface 46 side is smaller than the radius of curvature of the curved portion 51. Also has a curved portion 50 having a large radius of curvature.

It is needless to say that the same effects as those of the overhead transmission line of the present invention can be obtained also in the overhead transmission lines of the first and second embodiments.

[0043]

EXAMPLES outer diameter D ₁ of the high-stepped protrusion 8 is 38.8 mm,
Open step h ₁ between the high step projections 8 and the low stepped flat portion 10 of the outer diameter D ₂ is 34.2 mm, the recess formed at the center of the low stepped smooth portion 10 is 2.3 mm, the high-stepped protrusion 8 Angle θ is 3
6 °, the depth H of the depression 12 formed between the formed aluminum wires 5 in the low step smoothing portion 10 is 0.9 mm, and the opening width t is
Was formed and the t / H was 5, an evaluation was made of wind noise characteristics, corona characteristics, and difficult snow deposition characteristics. As a result, the wind noise level and corona noise level were practically sufficient. In addition, the result that it was difficult for snow to reach the electric wire surface was obtained.

[0044]

In summary, according to the present invention, according to the present invention, the shape of the high step protrusion, the step between the high step protrusion and the low step smooth part, the opening angle of the high step protrusion, and each molded aluminum element in the low step smooth part By appropriately setting the depth of the dent formed between the lines, the opening width of the dent, and the ratio of the opening width to the depth, it is possible to maintain good wind noise characteristics and corona characteristics while maintaining the surface of the imaginary snow. An excellent effect that a transmission line can be obtained is exhibited.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an overhead transmission line 1 according to the present invention.

FIG. 2 is an enlarged view of a depression 12 in FIG.

FIG. 3 is an enlarged view of a depression 32 in a cross-sectional view of the overhead transmission line according to the first embodiment.

FIG. 4 is an enlarged view of a depression 42 in a cross-sectional view of the overhead transmission line according to the second embodiment.

FIG. 5 is a diagram illustrating a relationship between an opening angle of a high step protrusion and a reduction amount of a wind noise level.

FIG. 6 is a diagram illustrating a relationship between a potential gradient (Gmax) on the surface of an overhead transmission line and a corona hum sound relative level.

FIG. 7 is a diagram showing a relationship between the depth of a depression formed between the formed aluminum wires in the low step smoothing portion and the relative level of the corona hum sound.

FIG. 8 is a diagram showing a relationship between a ratio (t / H) between an opening width and a depth of a depression and an inclination angle.

FIG. 9 is a cross-sectional view of a steel core aluminum stranded wire as a conventional overhead transmission line.

FIG. 10 is a cross-sectional view of a conventional low wind noise electric wire.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Overhead power transmission line 2 Steel wire 4,5,6a, 6b, 7 Formed aluminum wire (formed wire) 8 High step projection part 10 Low step smooth part 12 Depression 26,36,46 Outer end surface 27,37,47 Both sides End surfaces 28a, 28b, 38a, 38b, 48a, 48b Corners on outer peripheral surface side 49 Linear portion 50, 51 Curved portion t Opening width H Depth

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kyoichi Suzuki 4-10-1, Kawajiri-cho, Hitachi City, Ibaraki Prefecture Inside the Toyoura Plant, Hitachi Cable Co., Ltd. (72) Inventor Hiroshi Kubokawa 5-chome, Hidaka-cho, Hitachi City, Ibaraki Prefecture No. 1-1 Hitachi Power Cable Co., Ltd. Power System Research Laboratories (72) Inventor Nobuaki Suga 4-10-1, Kawajiri-cho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Toyoura Plant F-term (reference) EF06

Claims (3)

[Claims] 1. A method of twisting an aluminum wire and a steel wire,
In the case of an overhead transmission line with twisted shaped strands with different heights on a part of the outermost strand and formed on the surface with a high step projection and a low step smooth part, the low step smoothing of the outermost layer of the overhead transmission line The depth H and the opening width t of the dent formed between the forming wires forming the portion are 0.7 mm ≦ H <1.5 mm, t
/ H ≧ 3, and t> 3.0 mm. 2. A cross section of a forming wire forming the low-stepped smooth portion is formed by closely contacting a smooth outer end surface forming an outer circumferential surface, an inner end surface forming an inner circumferential surface, and an adjacent forming wire. The inner peripheral surface side connecting the linear portions of the both end surfaces and the inner end surface and the linear portions of the both end surfaces are formed by forming the linear end portions having the linear portions coincident with each other in the radial direction of the electric wire. 2. The overhead transmission line according to claim 1, wherein a corner on the outer peripheral surface connecting to the outer end surface is formed in a straight line or a curved line, and a recess is formed between the corner and the adjacent outer peripheral surface. 3. A cross-section of a forming element wire forming the low-stepped smooth portion is substantially in contact with a smooth outer end surface forming an outer peripheral surface, an inner end surface forming an inner peripheral surface, and an adjacent forming element wire. The inner peripheral surface side connecting the linear portion of the both end surfaces and the inner end surface is formed in a straight line or a curved line. In addition to forming the corner on the outer peripheral surface side connecting the linear portion on both side end surfaces and the outer end surface in a straight line, forming both ends of the linear portion of the corner in a curved shape, and forming the corner on the adjacent outer peripheral surface side. The overhead transmission line according to claim 1, wherein the overhead transmission line forms a depression.